Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Update neutron delete_neutron_net function." into stable/fraser
  - Update neutron delete_neutron_net function.

    Update the changes done in patch [1].

    JIRA: YARDSTICK-890

    [1] https://gerrit.opnfv.org/gerrit/#/c/52361/

    Change-Id: Iccbf16d0a2e72919d5092366241ff41686f01a58
    Signed-off-by: Shobhi Jain <shobhi.jain@intel.com>
    (cherry picked from commit 14615e286e67ca74a8c0ae55ffe043170e5ecbb6)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 0c92fe2..135f472 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 0c92fe258937aa056ccbc138bd819c15705b3469
+Subproject commit 135f47250e9253d5065fa4c51550d131739412ec